I can measure when I get home tonight. But from memory, the widest part of the magnet is not the deepest part. It tapers. If you're really trying to squeeze them as tight as possible, you can take advantage of this.
I hope this helps. Let me know if you need anything more. Please be aware that taking these measurements with a tape measure is pretty tricky and imprecise, so don't treat these values as exact. They should be pretty close, but don't design your drivers to be line to line or anything. I also have no idea what the sample to sample variation might be like on these things.